The present invention relates to a capstan bearing device for the purpose of making a tape recorder ultrathin.
In a tape recorder, a capstan shaft is integrally provided with a flywheel for stabilizing rotation of the capstan shaft and for driving the capstan by a driving source through the flywheel.
In this case, as a bearing device of the capstan shaft, use is often made of an assembly formed by fixing a bearing member 3 with an oilless metal 2 to a chassis 1, inserting a capstan shaft 5 integrated with a fly-wheel 4 from the lower side or the upper side of the bearing member 3 and suitably adjusting a thrust pad by a thrust screw 6 as shown in FIG. 1 in a tape recorder with the use of a so-called compact cassette.
On the other hand, in a tape recorder which utilizes a micro cassette, there is used a bearing device wherein a bearing member 3 is fixed to a second chassis 7 and a thrust pad 8 is integrally formed with the bearing member 3 as shown in FIG. 2. To the thus formed bearing member 3 is inserted a capstan shaft 5 integrated with a flywheel 4 from the upper portion.
Since the conventional bearing device is composed of an oilless metal and a bearing member for holding the oilless metal as described above, the outer diameter of the device is liable to become enlarged. In a device using two chassis, this bearing device is an obstacle to reducing the thickness of the tape recorder.
Therefore, if a tape recorder is to be made thin, the capstan shaft cannot be shortened. Thus, if it is desired to make the bearing short, and if the bearing is made extremely short, the capstan shaft is twisted by the pressing force of a pinch roller at the time of recording or reproducing, thereby inducing an increase in the consumption of current, and deterioration of the durability of the device.
Therefore, it is proposed to extend a part of the capstan shaft into the tape cassette and this approach is utilized in the present invention. In this case, an oilless metal is generally used, and a part of a bearing 31, i.e., an extended portion 31a, is inserted into a cassette 32 as shown in FIG. 7. However, there exists the possibility of breaking that portion because the oilless metal extended into the cassette 32 is too thin. Further, since the oilless metal is exposed, there is the possibility of oil adhering to a tape when inserting or releasing a tape cassette, so that it is necessary to coat a vinyl tube on the extended portion 31a or to foam a film such as liquid teflon or the like.